Field of Invention
The present invention relates to a high strength glass fiber which belongs to a technical field of material science.
Description of Related Arts
With the continuous development of wind power technology, the low-cost large-scale production of the high-strength fiber has attracted more attentions of manufacturers. The key of the low-cost large-scale development of the wind power is to reduce the difficulty of fiber drawing process, and simultaneously to ensure that the fiber meets the high-strength requirements of large-size fan blades. Therefore, the developed countries, which are advanced in the wind power technology, focus on the research of the high-strength fiber to resolve the large-scale of the fan blades. Currently, the high-strength fiber is mainly divided into two types: carbon fiber and glass fiber. Although the carbon fiber has good insulation and corrosion resistance, it has high production cost and complex process. The glass fiber has not only high mechanical strength, but also low production cost, so that it is suitable for large-scale production. Thus, glass fiber has become the research hotspot of the high-strength fiber in last decades.
The first high-strength glass fiber can be traced back to the S series of glass fiber developed by the United States AGY Corporation in 1968, which is researched and developed to meet the need of military development. Then other countries have also developed similar high-strength glass fiber, such as Japanese “T” fiber, French “R” fiber and Chinese “HS” series of fiber. These high-strength glass fibers have very excellent mechanical properties. However, they are unable to achieve large-scale production in the modern tank furnace due to too high molding temperature and large production difficulty, which limits their applications in the military field.
In the 21st century, the glass fiber industry has been flouring and the market continues to expand. The major glass fiber companies have developed new generations of high-strength glass fiber. At the same time, the theoretical level, the production equipments and the fabrication technology of the glass fiber are also continuously improved. Currently, the best high strength glass fiber is SiO2—Al2O3—MgO—CaO series. For example, the U.S. Pat. No. 3,402,055 discloses a high strength glass fiber whose component is 65% SiO2, 25% Al2O3 and 10% MgO, is adapted to the formation of S-2™ glass. The new single-filament strength of this glass fiber is 4600-4800 MPa. The upper crystallization temperature is 1464° C. and the fiber drawing temperature is 1471° C., which indicates the fiber possesses high mechanical strength and good high-temperature performance. However, the melting temperature and fiber it is not easy to draw fiber because of its large viscosity and high drawing temperature, which results in the high production cost.
In order to reduce the melting temperature and wire drawing temperature of the glass fiber, the major glass fiber companies and research institutes tend to add a various fluxing agent, in the basis of SiO2—Al2O3—MgO—CaO substrate. For example, Advantex™ glass fiber, produced by Owens-Corning Co., Ltd., comprises 59-62% SiO2, 20-24% CaO, 12-15% Al2O3, 1.0-4.0% MgO, 0-2% Na2O, 0-2% K2O, 0-0.9% TiO2, 0-0.5% Fe2O3 and 0-0.9% F. A large amount of fluoride and alkali metal oxide are introduced into the glass system, so that the melting temperature and the wire drawing temperature are greatly reduced. The melting temperature, the upper crystallization temperature and the wire drawing temperature of the glass are 1480° C., 1204° C. and 1260° C., respectively. However, because a large amount of fluoride and alkali metal oxidation are introduced into the glass, the new single-fiber ecological strength is only 3100-3800 MPa. The domestic HS series glass fiber is similar to the Advantex™ glass fiber. The composition of the HS series glass fiber is as follows: 52-66% SiO2, 16-26% CaO, 12-16% Al2O3, 5-10% H3B03, 0-5% MgO, 0-2% Na2O+K2O, 0-0.8% TiO2, 0-5% Fe2O3 and 0-1.0% F. A large amount of alkali metal oxide, fluoride and boric acid are introduced into the HS series glass system, so that the melting temperature and the wire drawing temperature of the glass are greatly reduced. The melting temperature and the wire drawing temperature of the glass are 1465° C. and 1350° C., respectively, and the new single-fiber ecological strength is only 3600-4000 MPa. Moreover, the composition of the French R-glass fiber is as follows: 59-62% SiO2, 20-28% CaO, 12-15% Al2O3, 1.0-4.0% MgO, 0-2% Na2O, 0-2% K2O, 0-2% CeO2, 0-0.5% Fe2O3, and 0-0.9% F. A large amount of Na+, K+, and Ce4+ are introduced into the French R-glass system to reduce the high-temperature viscosity and melting temperature. The melting temperature and the wire drawing temperature of the glass are 1450° C. and 1280° C., respectively, and the new single-fiber ecological strength is only 3200-3400 MPa.
Therefore, while ensuring the high strength of glass fiber, reducing the glass melting temperature and wire drawing operation temperature has important significance for mass production and reducing energy consumption.